Autonomous glider for landing of meteorological radiosondes

We are researching this idea about landing high altitude radiosondes back to where they are launched. Radiosondes are a meteorological equipment, launched with a weather balloon. They are lost almost every time, sometimes landing hundreds of kilometers away from the initial launch cite.
While researching we found this project -
It seems dead, but they seem to have proven it is possible to launch and land such a device.
The main requirment for such a glider are:

  1. Minimum weight - the bigger the weight the bigger the balloon you need and the more gas you need to inflate it.
  2. Operation in low temperature. During the flight the temperature can fall to -60.
  3. There should be a release mechanism to drop the glider before the balloon burst.
  4. It will not manage to land from where it started in strong winds, but it can always land somewhere else. There should be a list of possible GPS locations to land.

So can such a glider be made? Do you have alternative ideas that will do the job? Would it be very expensive?

The cost of the parts for the glider with good quality components is around 200 - 250 $ while the cost for developing the system and running test is much , much higher.
It is not a simple project.
I wonder if with difficult conditions, i.e headwinds , this solution might have still some sense .